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The Basic Idea
Bluetooth is a standard for a small , cheap radio chip to be plugged into computers, printers, mobile phones, etc
Bluetooth chip is designed to replace cables.Information normally carried by the cable, is transmitted at a special frequency to a receiver Bluetooth chip.
These devices can form a quick ad-hoc secure “piconet” and start communication.
Connections in the “piconets” can occur even when mobile.
A collection of devices connected via Bluetooth technology in an ad hoc fashion.
A piconet starts with two connected devices, and may grow to eight connected devices.
All Bluetooth devices are peer units and have identical implementations. However, when establishing a piconet, one unit will act as a Master and the other(s) as slave(s) for the duration of the piconet connection.
Low cost as cables – chip $5
Secure as cables – must support authentication and encryption
Must support both data and voice.
Must connect to a variety of devices.
Must be able to function in a noisy environment.
Data rates – 721kbps , using the 2.45Ghz radio frequency band –I.S.M (Industrial, scientific and medical)
Must support many simultaneous and private “piconets”.
Must be low power, compact and global.
Core Specification -Deals with the lower layers of the architecture and describes how the technology works.
Profile Specification -
Focuses on how to build interoperating devices using the core technology.
One radio performs a page function on a special Inquiry ID global address.
Listening radios perform an inquiry scan on a unique sequence of 32 channels.
The radio will listen every 1.25 seconds on each of these 32 channels for 10ms and will then repeat the same for the next channel.
The inquiring radio issues a number of pages on the inquire channels and then listens for a response for 1.25 seconds for 16 of the 32 channels.
Authentication and encryption is provided at the Link Manager layer.
The PIN is translated into a 128 bit link key which is used for authentication.
After authentication the radios will settle on a suitable length encryption key to be used.
Bluetooth relies on PIN codes to establish trusted relationships between devices.